Device for sensing physiological signal and method for sensing the same

ABSTRACT

A device for sensing a physiological signal comprises: two sensing units connected to the palms a subject respectively to receive a first electrocardiogram (ECG) signal; a filter for generating a second ECG signal by filtering the first ECG signal; an amplifying unit for generating a third ECG signal by amplifying the second ECG signal; an analog to digital converting unit for converting the third ECG signal into a digital signal; an operating unit for generating a plurality of analysis data by operationally analyzing the digital signal; and a display unit for displaying the plurality of analysis data. Therefore, the accuracy of the ECG is improved and the operation is simplified.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a physiological signal sensing device,and more particularly, to a device with its sensing method that is easyto operate for sensing physiological signals and improving the accuracyof records for electrocardiogram (ECG).

2. Description of the Related Art

It is known that the heart is an organ composed by muscles. However, themuscle that composes heart is different than other muscles (striatedmuscle, such as arms, legs, chest muscles). It is called “myocardium”.When the heart is active, current is generated by heart beating andelectrocardiogram (ECG) is a picture that records the change of thiscurrent.

From ECG, we can diagnose the shape changes of heart caused byarrhythmia and all kinds of heart diseases. From the changes of ECG, wecan know whether the heart beating is regulative or not (i.e.arrhythmia). The main reason of causing arrhythmia is when there is aproblem at a certain part or point of conduction system in heart. Fromthe changes of different ECG pictures, we can understand which point ofthe conduction system is abnormal. In addition to the conduction systemdiseases, the changes of electrocardiogram follow the heart shapechanged by whatever reasons. For example, when the workload of the heartis increased by long-term high blood pressure or heart valve diseases,myocardium hypertrophies will be thickened to cope with the increasedworkload. Meanwhile, the current of heart is also changed so as tochange the shape of ECG. Therefore, from the changes of ECG, we can knowif there is myocardium hypertrophy and also indirectly know if there isany cardiac disease to increase the workload of myocardium.

The present electrocardiogram or heart rate variability analysisfacilities all complete the analysis and the collection of theelectrocardiogram by customized lines and a customized program. Thesecustomized lines are comprised of complex amplifier circuit, and theanalysis programs which are expensive and customized as well have to runin the very expensive PC or workstation.

The price of hardware-related is often more than ten thousand NTD, andthe price of computer is above twenty thousand NTD. The range of theprice of software is large, which can range from two thousand to onemillion NTD. The total cost is extremely high, which would cause seriouslimit and impact on extension and application of this technology.

Because most of the electrocardiogram measuring instruments are veryexpensive and the size is large, most of the ECG is operated inhospitals; and very few people would like to purchase one to put athome. It would cause inconvenience to the people.

Therefore, it is desirable to let people gain their own ECG correctly atany time without going to a hospital, which is a useful direction ofthinking.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a physiological signalsensing devices and sensing methods in order to improve the accuracy ofECG records and make it easy to operate.

In order to concretely describe the present invention, a physiologicalsensing device is provided, which includes:

two sensing units connected to two palms of a subject respectively forreceiving a first ECG signal;

a filter unit for generating a second ECG signal by filtering the firstECG signal;

an amplify unit for generating a third ECG signal by amplifying thesecond ECG signal;

an analog to digital conversion unit for converting the third ECG signalto a digital signal;

an operating unit, comprising: a QRS wave sieving unit for sieving aplurality of consecutive QRS waves from the digital signal;

a heart beat measurement unit for generating a heartbeat cycle signalaccording to the QRS waves;

a time-domain analysis unit for generating a time-domain analysis dataaccording to the heartbeat cycle signal;

a Fourier analysis unit for generating a Fourier analysis data,according to the heartbeat cycle signal;

a PQRST wave sieving unit for sieving a plurality of consecutive PQRSTwaves from the digital signal; and

a PQRST wave analysis unit for generating a ECG analysis data accordingto the PQRST waves; and

a display unit for displaying the time-domain analysis data, the Fourieranalysis data and the ECG analysis data.

According to another embodiment, the present invention provides asensing method of a physiological sensing device, comprising the stepsof:

connecting the physiological sensing device to two palms of a subjectrespectively through two sensing units for receiving a first ECG signal;

generating a second ECG signal after filtering the first ECG signal;

generating a third ECG signal after amplifying the second ECG signal;

converting the third ECG signal into a digital signal;

sieving a plurality of consecutive QRS waves from the digital signal;

generating a heartbeat cycle signal according to the QRS waves;

generating a time-domain analysis data according to the heartbeat cyclesignal;

generating a Fourier analysis data according to the heartbeat cyclesignal;

sieving a plurality of consecutive PQRST waves from the digital signal;

generating a ECG analysis data according to the PQRST waves; and

displaying the time-domain analysis data, the Fourier analysis data andthe ECG analysis data by a display unit built in the physiologicalsensing device.

In order to better describe the features and advantages of the presentinvention mentioned above, embodiments will be provided below withreference to appended drawings to better describe the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an operation diagram of the physiological signal sensingdevice according to the present invention.

FIG. 2 is a function block diagram of the physiological signal sensingdevice according to the present invention.

FIG. 3 is a function block diagram of the operating unit according tothe present invention.

FIG. 4 is the wave diagram of the present invention.

FIG. 5 is a display diagram of the analysis data according to thepresent invention.

FIG. 6( a)-6(f) are appearance diagrams of the physiological signalsensing device according to the present invention.

FIG. 7 is the implementation flow chart of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Each heartbeat cycle generates three distinct EKG (electrocardiogram)waves, which respectively are P wave (atrial depolarization, that is,potential difference generated by depolarization before the atrialcontraction occur), QRS wave (ventricular depolarization, that is thebeginning of the myocardial depolarization, which is the beginning ofventricular contraction) and T wave (ventricular re-polarization—whenmyocardial cells depolarize, they will be a period of time for refusingaccept any further stimulation).

These waves are not action potential, but to represent the potentialchange between the two regions on the heart surface, which is an effectgenerated by mixing up a lot of the action potential of myocardialcells. For example, we can know that atrial depolarization generates apotential difference by up-deflection of EKG line; therefore, theup-deflection of EKG line reaches the maximum level when half of theatrial is depolarized.

EKG line returns back to the baseline when all of the atrial depolarizebecause the whole atrium area is in the same polarity. Hence atrialdepolarization causes P wave. The action potential is transmitted toventricular and establish a similar potential difference, which causes arapid upward deflection EKG line, and then back to the baseline afterthe whole ventricular is polarized. Hence, the ventriculardepolarization can be represented by QRS wave. The plain period ofmyocardial cells action potential is equivalent to ST-segment of EKG.Finally, T-wave is generated by the re-polarization of ventricular.

ECG waveforms and their appearing times might be affected by thetransmission of electrical signals changes caused by many kinds ofcardiac defects. That is why we must rely on ECG to diagnose some heartdiseases. Autonomic nervous system controls the body and life tomaintain the physiological functions including blood pressure, heartrate, trachea resistance, perspiration, body temperature, energymetabolism, and those nerve controls can be operated unconsciousness.

Autonomic nervous system is divided into two major parts, sympatheticand parasympathetic nervous system. In general, the former is related toagainst environment, and the latter related to living and propagation.

For example, the excitement of former would raise blood pressure anddilates pupils, and the excitement of latter would facilitate thesecretion of gastrointestinal and genital erection and so on. Ingeneral, the sympathetic and parasympathetic nerve systems are bothprosper in youth and both fading in old age. However, sympathetic nerveis stronger than parasympathetic nerve in male and vice versa in female.It is obvious that sympathetic and parasympathetic nerve systems have aclose connection with daily work and rest of human body.

If the autonomic nervous is disorder, a variety of acute or chronicdiseases might be caused, such as heart disease and high blood pressureand so on, that will in turn lead to a serious emergency case, such assudden death. As a result, to keep autonomic nervous system healthy isan important issue in medicine.

In recent years, many new diagnostic techniques for autonomic nervoussystem have been successfully developed.

Due to the maturity of computer technology and spectrum analysis,autonomic nervous system functions of heart can be detected andquantified through small changes in heart rate, that is, heart ratevariability (heart rate variability, HRV) when a human body is in rest.In other words, we can analyze or diagnose a normal person's autonomicnervous system function without interfering in his daily routine.

Some method of computing heart rate variability is analysis in thetime-domain such as The Standard Deviation of Normal to NormalIntervals, SDNN; and some are assisted by spectral analysis.

Researchers found out that the fluctuate routes of the smallfluctuations in heart rate variability can represent total power (TP).And those fluctuations may also be clearly divided into two groups,high-frequency (HF) and low-frequency (LF) components. In which the highfrequency component synchronizes with animal's respiratory signal, so itis also known as the respiratory component. Low-frequency component isconjectured to have a connection with blood vessels movement andpressure sensing reflex. Some scholars further divide low-frequencycomponent into very low frequency (VLF) and low-frequency components.

Referring to FIG. 1, FIG. 2 and FIG. 3, the physiological signal sensingdevice 10 of the present invention substantially consists of two sensorunits 11 and 11′, a filter unit 12, an amplifying unit 13, an analog todigital conversion unit 14, a operating unit 15 and a display unit 16.

The two sensor units 11 and 11′ are attached to two palms of a subject(or a human being) 20 or held in hands of the subject 20 respectivelyfor receiving a first ECG signal Sig1 and Sig1′ generated by user'sheartbeat (Sig1 and Sig1′ are left-hand and right-hand ECG signal). Thefilter unit 12 filters the first ECG signal, Sig1 and Sig1′ to generate,and keeps the second ECG signal Sig2 from the outside interference togenerate noise. The amplifying unit 13 amplifies the second ECG signalSig2 to generate a third ECG signal Sig3, so as to facilitate follow-uptreatment.

The analog to digital conversion unit 14 converts the third ECG signalSig3 into a digital signal Sig4 (The first ECG signal Sig1 generated byuser's heartbeat is analog and it is easy to compute after convertinginto digital signal). The operating unit 15 processes the digital signalthrough a series of operations to generate a plurality of analysis dataSig6, which are output by a display unit 16.

The physiological signal sensing device 10 of the present invention ismainly for measuring ECG signals from two palms. As the palm skin is themost delicate and the thinnest place of hands, so that the presentinvention is developed by using palm as the measuring and recordingpoint to get the most accurate record of the electrocardiogram.

The hardware design of the present invention adopts bipolar inputmethod, namely, to use two sensor units 11 and 11′ (no matter by wireconnection or direct configuration on both sides of physiological signalsensing device 10) as the input of ECG signal to enhance the intensityof ECG signal input. If setting two sensing units 11 and 11′ on bothsides of the physiological signal sensing device 10, both sensing units11 and 11′ are dry electrodes and can be constituted by metals,electrical conductivity rubber or conductor.

The way of collecting ECG signals from palms has following advantages:

1. The way of two hands fingers crossing to form a bowl-shaped allowingmuscles of two hand to relax and rest, and the result of relaxation makeautonomic nervous system function easy into a steady situation, withoutstimulating sympathetic activity by the measurement itself, so as toensure that the measurement is more accurate.2. As the muscles relax, the interference of EMG will also besignificantly decreased.3. As two hands form a bowl-shaped, it also forms a shield to fightagainst radio interference to reduce noise when collecting ECG signal.4. As two hands form a bowl-shaped, it can cover the surrounding lightso that the ECG display on-screen will be cleared and in addition,keeping the privacy of individuals due to spectators will not easy tosee the individual physiological signal.

The operating unit 15 substantially consists of a QRS wave sieving unit151, a heartbeat cycle measurement unit 152, a time domain analysis unit153, a Fourier analysis unit 154, a PQRST wave sieving unit 155 and aPQRST wave analysis unit 156.

QRS wave sieving unit 151 sieves a plurality of consecutive QRS wavesfrom the digital signal. The heartbeat cycle measurement unit 152generates a heartbeat cycle signal based on the QRS waves. Thetime-domain analysis unit 153 generates a time-domain analysis databased on the heartbeat cycle signal. The Fourier analysis unit 154generates a Fourier analysis data based on the heartbeat cycle signal.The PQRST wave sieving unit 155 sieves a plurality of consecutive PQRSTwaves from the digital signal and the PQRST wave analysis units 156generates an ECG analysis data based on the PQRST waves. The Time-domainanalysis data, the Fourier analysis data and the ECG analysis data arethe basic data of the analysis data Sig6.

In addition, the physiological signal sensing device 10 is configuredwith an extension unit 17 for allowing to insert a memory card forstoring the time-domain analysis data, the Fourier analysis data and theECG analysis data of the subject 20 after measuring for futurecomparison.

Further, the physiological signal sensing device 10 is configured with aswitch unit 18 for switching the information shown on the display unit16.

Also, the physiological signal sensing device 10 is configured a batteryunit 19 which provides electrical power for the requirement ofphysiological signal sensing device 10 operation. And the battery unit19 is a lithium battery or any kind of battery which can be charged anddischarged.

Referring to FIG. 4 and FIG. 2, the QRS wave sieving unit 151 sieves twoconsecutive digital signals Sig4 to two QRS waves, that is, twoheartbeat signal of the testee.

The heartbeat cycle measurement unit 152 measures the intervals of R-Rwave between two QRS waves for generating the heartbeat cycle signal,and the time-domain analysis unit 153 as well as Fourier analysis unit154 are in accordance with the heartbeat cycle signal to processcalculation.

The time domain analysis unit 153 carries out the analysis of theheartbeat cycle such as standard deviation of all NN intervals, SDNN,Standard deviation of the averages of NN intervals in all 5-minutesegments of the entire recording, SDANN, the square root of the mean ofthe sum of the squares of differences between adjacent NN intervals,RMSSD, mean of the standard deviations of all NN intervals for all5-minute segments of the entire recording, SDNN index, standarddeviation of differences between adjacent NN intervals, SDSD, number ofpairs of adjacent NN intervals differing by more than 50 ms in theentire recording, NN50 count, NN50 count divided by the total number ofall NN intervals, pNN50 to generate the time domain analysis data. Thetime-domain analysis data will be generated and showed on the displayunit 16 in FIG. 5.

The Fourier analysis unit 154 carries out the analyses of heart rhythmcycle signal for power spectrum density of the total power (Total powerof HPSD, TP), extremely low frequency rhythm power spectrum density(Very low frequency of HPSD, VLF), low-frequency rhythm power spectrumdensity (Low frequency power, LF), high-frequency heart-power spectrumdensity (High frequency power, HF), high-frequency low-ratio (Lowfrequency power to HF ratio, LF/HF), low-frequency standard (normalizedLF, LF %), high-frequency standard (normalized HF, HF %) to generate theFourier analysis data as shown on the display unit 16 in FIG. 5.

The PQRST wave sieving unit 155 sieves the digital signal Sig4 into oneor more PQRST waves. The PQRST wave analysis units 156 will becalculated according to the PQRST, as well as the high point of time(such as P point height (A_(P)), Q point height (A_(Q)), R point height(A_(R)), S point height (A_(S)), T point height (A_(T)), RR interval oftime (T_(PR)), QT interval of time (T_(QT)), QS interval of time(T_(QS))), and so on to generate an ECG analysis data displayed on thedisplay unit 16 as shown in FIG. 5.

Referring to FIGS. 6( a)-6(f), because the filter unit, amplifying unit,analog to digital conversion unit and operating unit of the presentinvention can be integrated into a single chip and the size of singlechip is very small, this physiological signal sensing device of thepresent invention can be made into very thin and short form, such asFIG. 6( a)-6 (f) of card, square, round, oval, egg-and-ball shape and soon, making it easy for users to easily carry.

In addition, the physiological signal sensing devices of the presentinvention can also be integrated into portable electronic devices suchas mobile phone, PDA (personal digital assistants), notebook computers,MP3 players, by merely embedding the single-chip into the devices aboveand installing two sensor units, and sharing display unit with abovedevices to become a multi-functional machine.

As a result, people do not need to go to hospitals for measuring ECGdata. The portable electronic devices can carry out and measure. It isvery convenient and practical with low manufacturing costs.

Moreover, the physiological signal sensing device can also carry outelectromyography (EMG), body temperature and blood sugar detections, todetect a variety of physiological signals for the purpose ofeffectiveness.

Referring FIG. 7, the sensing method of physiological signal sensingdevice comprises the following steps: connecting two sensing units totwo palms of a subject respectively for receiving a first ECG signal(S1), that is generated by the subject's heartbeats; then generating asecond ECG signal (S2) by filtering the first ECG signal, such that thesecond ECG signal is kept from generating noise due to outsideinterference; and then generating a third ECG signal by amplifying thesecond ECG signal (S3), so as to facilitate follow-up treatment; thenconverting the third ECG signal to a digital signal (S4) (Due to thefirst ECG signal arising from the user's heart rate is analog,calculation is made easier after converting the signal into digitalsignal); and sieving a plurality of consecutive QRS waves from thedigital signal (S5) from the consecutive digital signal; generating aheartbeat cycle signal according to the QRS waves (S6); generating atime-domain analysis data according to the heartbeat cycle signal (S7);generating a Fourier analysis data according to the heartbeat cyclesignal (S8); sieving a plurality of consecutive PQRST waves from thedigital signal (S9); generating a ECG analysis data according to thePQRST waves (S10); and displaying the time-domain analysis data, theFourier analysis data and the ECG analysis data by a display unit builtin the physiological sensing device (S11).

Although the present invention has been disclosed above with theembodiments, they are not intended to limit the invention. Any ordinaryskilled person in this field can make some modifications and improvementwithout departing from the spirit and scope of this invention.Therefore, the scope of this invention is defined by the appendedclaims.

1. An device for sensing a physiological signal comprises: two sensingunits connected to two palms of a subject respectively for receiving afirst electrocardiogram (ECG) signal; a filter for generating a secondECG signal by filtering the first ECG signal; an amplifying unit forgenerating a third ECG signal by amplifying the second ECG signal; anAnalog to Digital converting unit for converting the third ECG signalinto a digital signal; an operating unit for generating a plurality ofanalysis data by operational analyzing the digital signal, comprising: aQRS wave sieving unit for sieving a plurality of consecutive QRS wavesfrom the digital signal, a heart beat measurement unit for generating aheartbeat cycle signal according to the QRS waves, a time-domainanalysis unit for generating a time-domain analysis data according tothe heartbeat cycle signal, a Fourier analysis unit for generating aFourier analysis data, according to the heartbeat cycle signal, a PQRSTwave sieving unit for sieving a plurality consecutive PQRST waves fromthe digital signal; and a PQRST wave analysis unit for generating a ECGanalysis data according to the PQRST waves; and a display unit fordisplaying the plurality of analysis data.
 2. The device of claim 1,wherein the heartbeat cycle measurement unit measures the intervals ofR-R waves between the two QRS waves for generating the heartbeat cyclesignal.
 3. The device of claim 1, wherein the time domain analysis unitcarries out the analyses of one of the heartbeat cycle such as standarddeviation of all NN intervals, Standard deviation of the averages of NNintervals in all 5-minute segments of the entire recording, the squareroot of the mean of the sum of the squares of differences betweenadjacent NN intervals, mean of the standard deviations of all NNintervals for all 5-minute segments of the entire recording, standarddeviation of differences between adjacent NN intervals, number of pairsof adjacent NN intervals differing by more than 50 ms in the entirerecording and NN50 count divided by the total number of all NN intervalsto generate the time-domain analysis data.
 4. The device of claim 1,wherein the Fourier analysis unit carries out the analysis of one ofheart rhythm cycle signal for power spectrum density of the total power,extremely low frequency rhythm power spectrum density, low-frequencyrhythm power spectrum density, high-frequency heart-power spectrumdensity, high-frequency low-ratio, low-frequency standard,high-frequency standard to generate the Fourier analysis data.
 5. Thedevice of claim 1, wherein the PQRST wave analysis units generates theECG analysis data by calculating high points of the PQRST wave andintervals between the high points.
 6. The device of claim 1, wherein thedevice for sensing a physiological signal is integrated into a mobilephone, a PDA, a notebook computer or a MP3 player.
 7. The device ofclaim 1, wherein the device for sensing a physiological signal can alsocarry out electromyography(EMG), body temperature and blood sugardetections.
 8. The device of claim 1, wherein the two sensing units areconnected to the device for sensing a physiological signal by two wires.9. The device of claim 1, wherein the two sensing units are configuredon both sides of the device for sensing physiological signal.
 10. Thedevice of claim 1, further comprises an extension unit for allowing toinsert a memory card for storing the time-domain analysis data, theFourier analysis data and the ECG analysis data.
 11. The device of claim1, further comprises a switch unit for switching the information shownon the display unit.
 12. A sensing method of a physiological signalsensing device comprising the steps of: connecting two sensing units totwo palms of a human being respectively for receiving a first ECGsignal; generating a second ECG signal by filtering the first ECGsignal; generating a third ECG signal by amplifying the second ECGsignal; converting the third ECG signal to a digital signal; sieving aplurality of consecutive QRS waves from the digital signal; generating aheartbeat cycle signal according to the QRS waves; generating atime-domain analysis data according to the heartbeat cycle signal;generating a Fourier analysis data according to the heartbeat cyclesignal; sieving a plurality of consecutive PQRST waves from the digitalsignal; generating a ECG analysis data according to the PQRST waves; anddisplaying the time-domain analysis data, the Fourier analysis data andthe ECG analysis data by a display unit built in the physiologicalsensing device.
 13. The method of claim 12, further comprises the stepof measuring the intervals of R-R waves between the two QRS waves. 14.The method of claim 12, further comprises step of carrying out one ofthe analyses of heartbeat cycle such as standard deviation of all NNintervals, Standard deviation of the averages of NN intervals in all5-minute segments of the entire recording, the square root of the meanof the sum of the squares of differences between adjacent NN intervals,mean of the standard deviations of all NN intervals for all 5-minutesegments of the entire recording, standard deviation of differencesbetween adjacent NN intervals, number of pairs of adjacent NN intervalsdiffering by more than 50 ms in the entire recording and NN50 countdivided by the total number of all NN intervals to generate thetime-domain analysis data.
 15. The method of claim 12, further comprisesthe step of carrying out one of the analyses of heart rhythm cyclesignal for power spectrum density of the total power, extremely lowfrequency rhythm power spectrum density, low-frequency rhythm powerspectrum density, high-frequency heart-power spectrum density,high-frequency low-ratio, low-frequency standard and high-frequency. 16.The method of claim 12, further comprises the step of analyzing theheight of P, Q, R, S and T points of the PQRST waves and intervalsbetween each point.